It is very important to prevent spread of an infection such as influenza or tuberculosis for a safe and secure social life. It is considered that these infections spread by suction of a splash containing a microorganism such as bacteria or viruses released from a body of a patient into the atmosphere into a body of another person. A powerful means for preventing spread of the infections is to find and isolate an infected person early. Various diagnostic methods are used in a medical site.
For example, in diagnosis of a respiratory infection such as influenza, a simple kit for sensing an antigen of a microorganism such as viruses or bacteria contained in a body fluid using an immunochromatography method is often used. However, the diagnosis using the simple kit requires collecting a body fluid by inserting a swab into the nasal cavity of a patient, and may be rejected, for example, by a very young patient due to pain. In general, a simple kit has a low sensitivity, and cannot necessarily secure a sufficient amount of antigen of a microorganism in a patient in an early stage of infection. When the amount of antigen of a collected microorganism is small, negative determination will be made. The activity of inserting a swab into the nasal cavity of a patient is a medical activity; therefore, the activity is limited to medical workers.
Therefore, a method for sensing a microorganism more simply has been demanded. With respect to this demand, a method for directly collecting a microorganism such as viruses or bacteria floating in the air from breath and sensing the microorganism optically has been proposed.
For example, PTL 1 describes a technique of a method for capturing a microorganism by a membrane method and sensing the microorganism. Specifically, a membrane (filter) having pores is disposed between two members of an upper surface part and a bottom part, and a microorganism included in a fluid and having a size larger than the pore is captured by this membrane. Thereafter, the captured microorganism is stained with a visualization reagent, and is imaged by a CCD camera for image processing, or is observed and analyzed using an electron microscope or the like.
In the method for directly collecting a microorganism in the air using such a membrane as described in PTL 1, a microorganism can be collected without giving pain to a patient, and the method is not a medical activity. Therefore, the method can be performed also by a person other than a medical worker. In addition, bacteria collected on the membrane is sensed directly. Therefore, collecting and sensing can be performed automatically and continuously.
PTL 2 describes a technique of an analyzer in which a target component is bonded to a spot on a chip by an antigen-antibody reaction or nucleic acid hybridization, a fluorescence dye is then bonded to the target component, and the fluorescence amount derived from the target component is measured with an optical system device. This analyzer includes a gap disposed for each spot on a stand for holding the chip in order to optically separate fluorescence derived from the target spot and fluorescence derived from an adjacent spot from each other. The gap functions as an optical mask.
In such a method for measuring the fluorescence amount of a measurement object such as DNA as described in PTL 2, it is possible to determine presence of the measurement object more rapidly than in image analysis. The measurement object can be sensed with high sensitivity by disposing a mask transmitting fluorescence derived from the measurement object and blocking fluorescence derived from a substance other than the measurement object.